exam #2 Flashcards
what are the components of soil?
organic matter, air, water, mixed particles
what are the 5 factors of soil formation?
5 factors: climate, topography, time, parent material, organisms
how is soil formed?
the weathering and erosion of rocks breaks down parent material, both rocks and organic decaying material over time, or sediments left by glaciers; layers eventually form and new organic material accumulates, contributing nutrients and soil structure; its a product of the interaction between rocks, living organisms, climate, topography, and time
what is humus?
decomposed organic matter that remains in soil for a long time; it helps structure and slowly releases nutrients
sand particles
largest particles, lots of space between them –> less water retention
clay particles
smallest particles, sticky, little space between particles –> high water retention
gravitational water
water in soil from precipitation that moves into soil from gravity, not available for plant uptake
capillary water
water that fills a soils micropores & held with moderate force
hygroscopic water
tightly held water that forms a thin film around individual soil particles; too tight for plants to draw, allows for water storage through cohesion
loam
mixture of clay, sand, silt
what are the 6 soil horizons?
O - loose partially decayed organic matter (topsoil)
A - mineral matter mixed w/ humus
E - zone of leaching
B - accumulation of minerals transported from above
C - partially altered parent material
R - bedrock (unwethered plant material)
4 pools of plant nutrients
for soil
soil minerals (major source of nutrients EXCEPT N)
organic matter
absorbed nutrients
dissolved ions
what are urban soils like?
high heterogeneity (variation), temp affected from urban heat effect, limited resource
what are some soil contaminants & their effects?
lead & arsenic from pesticides and paint, higher concentrations in inner cities, get absorbed through plant uptake and groundwater
what are strategies to mitigate soil contamination?
add mulch/organic matter, lime to increase pH, use diff tilling practices, place gardens away from industrial areas
what is the rate of soil erosion determined by?
rainfall, soil erodibility (ease at which water percolates through soil), slope length, land cover, erosion control particles, distribution of water among precipitation events/timing
what are the social costs of poor soil practices?
eutrophication and siltation of streams
what is the difference between soil and dirt?
soil is more complex than just dirt, as it involves water content, particle size, organisms, microorganisms; they are living systems and provide all nutrients for plant growth
where do new species come from?
allopatric speciation - population becomes geographically isolated from parent population ex. galapagos finches
sympatric speciation - two groups live in the same area but evolve into different species ex. based on available niches (insects, apple maggot)
what drives speciation?
random drift (genetic drift) random changes in gene pool & natural selection
species richness vs species eveness
species richness refers to the amount of different species in an ecosystem (measure of biodiversity) while species evenness refers to the distribution of individuals among species
why is it not enough to report only species richness when assessing biodiversity?
it does not consider the abundance or distribution of species, or the variety of ecological functions and roles that species play within an ecosystem, genetic diversity within individual species; species eveness can be an indicator of how stable an ecosystem is, having balance contributes to the overall health & balance of an ecosystem
why are there more species near the equator?
climate stability + consistent sunlight = constant env to thrive in, higher rates of photosynthesis create greater levels of productivity –> more resources and energy able to be cycled, lack of extreme seasonal variations = easier to survive
how are species distributed?
endemic species which are restricted to a particular region and thought to have originated from there, then dispersal = movement of individuals from their birth site to other breeding sites or from one breeding site to another
describe the species-area relationship
the # of species in an area increases with area size, leading to more diverse habitats, less issues with disturbances, larger populations supported, and more potential for allopatric speciation
describe the species-energy relationship
terrestrial biomes: NPP peaks near equator and declines with latitude
marine environments: in coastal areas, follow terrestrial pattern; for deeper waters, biodiversity peaks at midlatitudes
biocentric vs anthropocentric
biocentric = value of species independent of their usefulness to humans
anthropocentric = value of species depends on usefulness to humans
what are ecosystem services of biodiversity?
pollinating flowers (majority of global crops rely on pollinators)
stabilizing climate
soil formation
controlling pests
what is the importance of biodiversity in agriculture?
important for food security in case of failure, has declined over time from selective breeding
IPAT equation
impact = population x affluence x technology
human threats to biodiversity
habitat conversion, habitat fragmentation, hunting becoming its own form of “natural selection” reversing actual natural selection by killing ones that have favorable traits to survive in the wild, predator control, wildlife trade
4 criteria for preserving biodiversity
- uniqueness (unique genetic composition)
- usefulness (commercial or cultural value)
- probability of extinction (how much effort is necessary to save the species)
- cost (to save the species)
in-situ vs ex-situ conservation
in-situ preserves species in natural habitat, ex preserves genetic material and conducts researchm
market based solutions to preserving biodiversity
ecotourism (contributes to conservation, operated with local communities for benefit)
biodiversity offsets - when development destroys habitat, a newer, bigger, better habitat must be restored/built
humans should act as land managers
null vs alternative hypothesis
null = no effect or change
alternative = discernable change
type I vs type II error
type I = false positive, rejects null hypothesis that is true (finds alternative hypothesis correct when it isn’t)
type II = false negative, accepts a false null hypothesis (shows no difference when there is)
weather vs climate
weather = temperature, precipitation, wind speed, cloud cover, humidity, pressure (at a particular time and place)
climate = patterns of weather conditions across an annual cycle
short wave radiation vs long wave radiation
short wave = light energy
long wave = infrared, sensible heat
short wave is reflected back as long wave & absorbed by GHG
atmospheric GHG
water vapor, CO2, methane, CFCs HFCs
radiative forcing
GHG potency determined by amt and frequency of infrared radiation it can absorb
what are the 2 largest sources of GHG?
electricity & heat production
aerosols
sulfates form aerosols (particles suspended in the air smaller than droplets) that reflect sunlight (short wave radiation), leading to cooling
why can’t CO2 fertilization happen indefinitely?
as heat becomes more of a limiting factor, there will be a slowing down of net absorption
what causes sea level rise (and what are some effects)?
melting of ice sheets on ground into ocean, water expands as it warms, increased runoff, storm surges have increased damage, natural tides are disrupted, subsidence (sinking of land under built cities)
4 categories of ecosystem services
supporting (nutrient cycling, soil formation, primary production)
provisioning (food, water, fiber, fuel $ value)
regulating (climate, flood, disease, water purification)
cultural (aesthetic, spiritual, recreation)
forest characteristics (state factors vs stochastic factors)
state = time, topography, parent material, climate, biota (expected state of ecosystem)
stochastic factors = extreme climate events, irruptions of native biota (push away from expected state)
forest ecosystem services
water quality, carbon storage, biodiversity, habitats, raw materials
why is snow important?
it provides insulation for soil and prevents it from freezing; lack of snow results in freezing, root/microbial mortality, accelerated nutrient loss & soil acidification
role of earthworms
invasive species from europe, they cause fundamental changes in soil properties: decrease soil, more vulnerable to erosion, diff seed bed, exposed roots
DISservices of forests
prevent agricultural land, opportunity costs, species invasions, forest fires
cut-down services of wood
materials (developed nations) & source of energy (developing nations)
standing service of wood
climate regulation, soil conservation, biodiversity
how do forests affect climate?
trees shape local temp and water availability through albedo & transpiration; removing them could heat or cool surroundings
less evaporation at a lower ambient temp, perform less photosynthesis from shorter growing system
- in short, influences rate of absorption of solar energy & at which water evaporates from the surface
how does moisture cycling work?
critical mechanism for rainfall to reach western amazon,
prevailing winds cause rising and cooling air & precipitation, evapotranspiration by trees contributes to precipitation
what are local rates of deforestation associated with?
conversion of forests to agricultural land, timber harvests, fires (accidental & deliberately set), energy & mineral production
water flow regulation in forests
floods
trees/plants slow soil erosion, less trees –> less soil retention, fast flowing water creates floods and carves channels, erodes soil & sediment with it
primary forest vs secondary forest
primary = late successional native forests containing most carbon and biodiversity
secondary = still regrowing, less biodiversity, less total C stock than primary forest but faster C sequestration rates
feed conversion efficiency
ratio of edible calories of animal product produced per cal of feed consumed by animal
FCE = cals of edible food produced / calories of feed consumed
does management of forests w/ continuous harvests increase or decrease the prevalence of forest fires?
INCREASE; harvest forests are not the same as wild intact ones: uniform rows, diff community composition, monoculture, same size/same age trees (one vulnerable, all vulnerable); continuous harvest increases dryness, increases winds, newly planted trees are not necessarily fire adapted